Why do you feel like you've been here before?

What is déjà vu?

Déjà vu describes the strange experience of a situation feeling much more familiar than it should. Here's an explanation of theories about why it happens.

Déjà vu is a memory illusion involving brain regions correcting inaccurate memories

Neuroscientists suggest the phenomenon is your brain recognizing that this feeling of familiarity is incorrect, showing off the brain's internal fact-checking system. Younger people experience déjà vu more often because their brains have higher excitatory activity and stronger memory monitoring systems.

What exactly is déjà vu?

While people have wondered about déjà vu for a long time, only recently have scientists started experimentally investigating what might trigger it. Read this deep dive into the latest science.

How science explains déjà vu

Take a fun look at the science explaining the odd experience of déjà vu, which some theories suggest is actually a sign of a healthy brain.

The doorway effect is when people forget their task when entering a new space

The "why did I come in here?" feeling after walking into a room comes from the brain creating event boundaries to organize memories. Mentally revisiting a previous room can help recall tasks and reverse memory loss. (Some readers may experience a paywall.)

Why does that bag look like a face?

If you've ever spotted a face hidden in an inanimate object, you've engaged in a timeless phenomenon known as pareidolia. This three-minute video explains why and how it happens.

Why do some people always get lost?

Using GPS, anthropological data, and VR, scientists have learned that one's sense of direction is largely influenced by upbringing. A person's wayfinding ability can be measured by how accurately they point toward an out-of-sight location, a challenge further complicated by imagining they're somewhere else and pointing toward a third location. Anxiety, safety concerns, and dislike of wandering can negatively impact one's sense of direction, which can improve with practice.

What it feels like to live with dementia

This nine-minute short film attempts to answer what it feels like to fade into dementia, as memory, motor skills, and cognition steadily decline. This award-winning short film follows Jos, a married father who worked in hospitality, as he sinks into ,"what feels like a single day. Or is it years?"

Why do we sometimes jolt awake before falling asleep?

Around 70% of people are estimated to experience the sensation of falling and jerking awake right as they're about to drift to sleep. That mysterious phenomenon is called hypnic jerking. As common as it is, hypnotic jerking remains disconcerting and hard to explain. While we don't yet have clear answers, peruse this article in Popular Science for some possible explanations as to why this happens.

Synesthesia: when sensation in one sense triggers an unrelated sense in the brain

The first reported clinical case of synesthesia dates back to the early 1800s, though the perceptual phenomenon may be much older than surviving records imply. This article by researcher Richard Cytowic details the scientific history of synesthesia, a neurological trait that causes some senses to overlap, giving color to numbers and flavors to names.

There’s a psychological explanation for ‘FOMO,’ or the fear of missing out

This video breaks down FOMO—what it is, how it works, and why it happens—showing how social comparison and uncertainty trigger anxiety that pushes people toward risk-taking and constant checking behaviors.

Smell is a robust memory cue for individuals with Alzheimer's disease

Odor is more effective than both visual and verbal cues for triggering autobiographical recall in Alzheimer's disease, according to 2021 research.

See this first-person virtual reality view of vertigo

This video shows a virtual reality environment view of what benign paroxysmal positional vertigo will look like, from a first-person view. It includes a virtual rendering of eye spinning associated with the condition. (Warning: Watching this may make some users feel a bit nauseous.)

Super recognizers may use specific facial features to commit faces to memory

Researchers believe that recognizing individuals seen only in passing, even decades later, is an ability of genetic origin and specific to facial recognition, rather than a result of better overall memory or perception. Applying eye tracking data from super recognizers to AI has led to improvements in facial recognition software.

While dreaming, the brain connects new information with already-stored memories

During dream sleep, the brain makes connections between new information learned during the day and information already stored in the mind, creating a revised mind-wide web of associations. The dreamer also temporarily becomes confused about time and place and is subjected to a pendulum of strong emotions.

To get that song out of your head, try distracting yourself or playing a new song

Around 90% of people experience getting a snippet of a song stuck in their head, also known as an earworm. Researchers think they are linked to memory, repetition, and inner rehearsal. Before written language, music was used alongside rhyming in many cultures to help people preserve oral histories.

Learn about the neuroscience and psychology of why we crave comfort foods

The term was coined in 1966, when psychologist Joyce Brothers suggested humans turn to food associated with the feelings of comfort from their childhoods when experiencing emotional distress. Since then, studies have shown that the familiarity, reliability, and convenience of certain foods from one's upbringing can become tied to feelings of nostalgia.

When common sounds become disturbing

Misophonia causes certain sounds to feel violating, triggering a "very visceral kind of experience" filled with extremely unpleasant emotions, including annoyance, anger, and disgust. A 2017 study found that people with misophonia have elevated activity in the brain's anterior insula—a region associated with interoception, emotional processing, and behavioral responses—when exposed to trigger sounds. Ongoing research suggests trigger sound context affects the severity and manifestation of the condition.

How to cope with postvacation blues

While it might seem counterintuitive, new research shows that experiencing exhaustion or a lack of motivation postvacation is fairly common. While travel itself can, of course, be tiring, the contrast between vacation freedom and endless Slack messages can be even more so. This article explores why the return-to-work existential crisis happens, and offers advice for beating the post-vaycay blues. Read it here.

Some art critics believe that Liminalism, a form of art exploring the uncanny yet familiar, defines our present moment

While analyzing images of abandoned malls or empty hallways, art historians and critics argue that this style captures the feelings of this moment in time. Liminalism, they propose, expresses prominent themes in our age like anonymity, alienation, and anxiety.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Mathematicians often solve problems using wordless mental processes

It's a common technique among expert mathematicians, where thinkers rely on intuition, blurry perceptions and subconscious work—no writing, no formulas. The state is distinct from daydreaming, and often relies on sudden illuminations stemming from extended periods of subconscious reflection.

The perception of haunted places is influenced by psychology, setting and suggestion

Gothic architecture and tragic histories contribute to the perception of hauntings. Infrasound and black mold can cause experiences reminiscent of paranormal phenomena. Although paranormal investigators use technology to seek natural explanations, many paranormal experiences remain non-falsifiable.

In the 'block universe' model, the past, present, and future exist simultaneously

According to special relativity, observers do not experience the same events in the same order, but all perspectives are valid. This means what is considered one person's as yet unexperienced future may have already taken place in someone else's past.

Near-death experiences bear similarities to the tradition of religious visions

Near-death experiences are often associated with Christian concepts such as heaven or angels, but people of all faiths (or lack thereof) have reported these events. This in-depth piece by Professor Atif Khalil examines the intersections of religion and science and the common elements in Western, often Christian, experiences with those of Eastern religions such as Islam and Buddhism.

The 'dupe' economy is fueled by the youthful thrill of thrift

Historically, you don't want people to know you have a knock-off luxury item. But today's younger generations are embracing the "dupe" economy, an open celebration of luxury knock-off items where consumers are proud to pay less for something roughly equivalent to premium brand offerings.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

When a Paris department store hesitated to sell Estée Lauder's perfume, she 'accidentally' broke a bottle, causing the smell to spread throughout the store and shoppers to start asking to buy the scent.

Existentialist writer Jean-Paul Sartre coined the famous phrase 'Hell is—other people' in his play 'No Exit'

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Dorothy's famous entrance into Oz in 'The Wizard of Oz' relied on analog tricks, including a body double and sepia-toned paint, as much as it did on technology

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Venture capital is a form of funding provided to early-stage companies with high growth potential, typically in exchange for an equity (or ownership) stake

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'